Since Fedora is a ISO image you need to use a application like Alcohol 120% or ISO Magic or Ultra ISO to help you burn it. If nero has the option to burn ISO's it will tell you. Nero Express doesnt have that option that is why you cant do it. So get one of the before mentioned apps and they will be able to burn the Fedora ISO for you.
I do not accept support questions via EMail, PM, IM or my G+ page!
Phone: LG Optimus G Pro
Running: Stock JB from LG with Nova Launcher